Belt and gear drive for high speed printer systems



y .5, 1965 A. D. M GREGOR ETAL 3,185,079

BELT AND GEAR DRIVE FOR HIGH SPEED PRINTER SYSTEMS I Filed Sept. 22, 1961 2 Sheets-Sheet 1 INVENTORS ARV/ND. McG/PEGOI? [04 E1 g. 4- 5421 e. 605715679 ATTORNEY y 25, 1965 A. D. MCGREGOR ETAL 3,185,079

BELT AND GEAR DRIVE FOR HIGH SPEED PRINTER SYSTEMS Filed Sept. 22, 1961.

2 Sheets-Sheet 2 INVENTORJ /0/ AIPV/IVD. McGAiGOR ATTOR/Vf United States Patent M 3,185,079 BELT AND GEAR DRHVE FGR HEGH SEEEB PEWTER SYSTEMS Arvin D. MrGregor, Birmingham, and Earl G. Goetseh,

Detroit, Mich, assignors, by n esne assignments, to

Control Data Corporation, Minneapolis, Minn, a corporation of Minnesota Filed Sept. 22, 1951, Ser. No. 139,93@ 4 Claims. (Cl. 101-93) This invention relates to printers for use with elec tronic computers, and particularly to a novel electromechanical, so-called on-the-fly type printer.

More specifically, this invention relates to the drive train employed in the printer disclosed in US. application Serial No. 138,157, entitled High Speed Printer, and filed on September 14, 1961, in the names of Arvin D. McGregor and James M. Irvine, Jr. To the extent that it may be necessary, the disclosure of the above application Serial No. 138,157 is incorporated herein by reference.

The printer disclosed in application Serial No. 138,157 includes a print drum on which rows of characters to be printed are formed and photoelectric means for indicating the location of any given row of characters. It also includes a mechanical amplifier type print hammer mechanism, the operation of which is effected by impact from a continuously rotated multiple lobe cam having magnetic means associated therewith for indicating the location of any given lobe. The printing occurs on the record strip or paper that is moved vertically a line or more at a time, and means are provided for actually driving the paper and for controlling the extent to which the paper is driven. The paper drive and the paper drive control means are driven through a common clutch mechanism.

Accordingly, an object of the invention is to provide means for driving the above mentioned elements of the printer in properly timed relation.

Another object of the invention is to provide a drive for the above purpose that lends itself to readily varying the relative speeds of the various elements, this being accomplished by providing for interchangeable belts and pulleys.

A further object of the invention is to provide a drive train for the above purpose which is relatively inexpensive to assemble in that low cost belts and pulleys are employed, rather than expensive gears.

Still another object of the invention is to provide a uniform velocity drive and to reduce the noise level by the maximum use of belts and pulleys, rather than gears which tend to backlash so as toresult in fluctuations in velocity and noise.

Another object of the invention is to employ belts and pulleys in certain portions of the drive to permit the print drum support arm to be pivotable from a print to a non-print position without in any way affecting or requiring subsequent adjustment of the drive train.

Another object of the invention is to provide a drive train having low inertia so as to reduce the load on certain elements of the drive and thereby enable faster and more precise operation of these elements than if heavier gears were employed.

Another object of the invention is to provide a printer drive train in which the paper advance mechanism and the paper advance control mechanism are driven simultaneously by the same clutch mechanism.

Still another object of the invention is to provide a printer in which the print drum mechanism, including the character signaling means, the print cam, including the lobe signaling means, and the clutch input are driven continuously by a main drive motor.

3,l85,79 Patented May 25, 1965 These and other objects of the invention will become more apparent upon reference to the following specifica tion and the attached drawings, wherein:

FlGURE l is a perspective view illustrating schemati cally a printer drive train embodying the invention;

FIGURE 2 is a cross-sectional view through a printer frame member in which portions of the drive train shown in FIGURE 1 are journaled.

FIGURE 3 is a more detailed fragmentary portion of FIGURE 1, with the print drum pivoted to the non print position.

FIGURE 4 is an enlarged cross-sectional view illus trating the print drum pivot.

Referring now to the drawings in greater detail, a drive train embodying the invention is comprised generally of an integrated belt, pulley and gear system tying together in non-slip and substantially vibration-free relation the main drive motor 167, the print hammer actuation cam lit-8, the print drum 1&5 and the paper drive and format control group mechanism 119; it includes various asso ciated speed changing, direction reversing and belt tensioning pulleys, gears and wheels, the location and purpose of which will be more fully described.

The various shafts on which the above mentioned gears and pulleys are mounted are supported in suitable bearings, such as bearings 111 (FIGURE 2), mounted in the end support 1452 extending from one end of the printer frame 1531. For example, shafts 115 and 116 of the paper advance mechanism, input shaft 117 and output shaft 113 of the spring clutch mechanism, and shaft 119 on which the intermediate pulley 12% is mounted are supported in the usual manner in the end support 102 by means of the hearings or other usual means shown in FIGURE 2.

It should be stated at the outset that all of the belts and pulleys employed in this drive train are of the Gilmer type; that is, the pulleys have evenly spaced teeth of uniform length engaging similarly formed notches on the inner surfaces of the belts associated therewith so as to provide a non-slipping, uniform velocity drive in each case. Maximum use is made of belt drives because they are less noisy and less expensive than gears; also, gears have a tendency toward fluctuations in velocity to the extent that their use is not desirable.

As mentioned before, a complete and detailed disclosure of a printer with which our invention can be used is found in the referenced application. However, a brief description of the print drum mounting (FIGURE 4) and of clutch 128 (FIGURE 2) is given below.

Print drum lllfi is hollow, fitting on end plates 393 (FIGURE 1), one of which has positioning lug 305 fitting in a notch in the drum. The other end plate (not shown) is movable axially of the drum to separably connect it to the driven end plate 303. Shaft 15% is fixed to plate 393 to rotate the latter. Bearing 301 is fitted on shaft 154 and is mounted in print drum arm 273 which is pivoted by shaft 274- in supports 1&2 and MM of frame 101. Pivot shaft 274 is pinned as at 27% to arm 273, requiring the shaft 2'74 to rotate as the arm 273 and drum 169 are rotated from a horizontal (print) to a vertical (nonprint) position. Torsion spring 275 is fixed at one end to shaft 274 and at its other end to support 102. The spring is a helper spring to facilitate lifting the arm and drum to the vertical position (FIGURE 3). When lowered the arm is latched down in the print position by a conventional latch (not shown).

Spring clutch 12$ couples a continuously rotating power input shaft ll? (FIGURE 2) to the power output shaft 118 under conditions prescribed by electrical control signals having no bearing on the invention claimed herein. The clutch members 394 and 492 are located in a cavity 393 and they are axially piloted as at 3%, 493 and 494. The clutch members are fixed to the respective shafts 118 and 117, and they have a spring 4% and. an actuating sleeve 4% concentrically mounted thereon. The spring is coupled to the clutch members 394 and to the actuating sleeve, and has an interference fit on clutch members 3% and 462. Thus, when sleeve 4% is freed for rotation (e.g. by a solenoid operated pawl, not shown) the spring winds tightly on'the clutch members in the manner of a self-energizing brake. Anti-backlash pin 415 pressed by spring 416 into engagement with ratchet teeth 400 requires the spring clutch to be precisely incremental in its operation. 7

A clear understanding of the drive train will be had upon examination of the schematic illustration of FIG- URE 1. It will be observed that the main motor pulley 121 drives the cam pulley 122 mounted on the cam shaft 123 directly through the belt 124. A smaller pulley 125 also mounted on the cam shaft 123 drives pulley 129 through the belt 126. A smaller pulley 127 is mounted on the same shaft 119 on which pulley 126i is fixed, and it drives a clutch device 128 through the belt 129 and a pulley 130 mounted on the clutch input shaft 117. The output shaft 118 of the clutch has two additional pulleys 13:4 and 135 mounted thereon, pulley 135 driving the format control sprocket 136 through shaft 417, its pulley 137 and belt 138 and pulley 134 driving the paper drive mechanism 139 through belt 1 23, pulley 142, gear 144 mounted on the same shaft 146 on which pulley 142 is fixed and a reversing gear 14-8 connected to the paper drive mechanism. Gear 1 is-mounted in the other end of shaft 119 on which pulley 120 is mounted, and this gear drives a meshing reversing gear 15% mounted on the shaft 151. Pulley 152 is also mounted on shaft 151, and it drives pulley 153 mounted on the print drumshaft 154 by means of belt 155 tensioned by the spring-loaded tensioning Wheel 156, FIGURE 3.

The drive motor 107 is operated, when power is supplied thereto, at a constant predetermined speed, the relatively heavy flywheel 112 mounted on cam shaft 123 serving the usual purpose of preventing fluctuations in rotational velocity. It is thus apparent that the cam 198 and the print drum 199 are driven at some constant related speeds that are proportional to the speed of the main drive motor 107, but that the operation of the paper drive and format group mechanisms are controlled by the operation of the clutch 128, the construction (FIGURE 2) and operation of which is fully described in application Serial No. 138,157. In other words, the cam 1538 and the print drum 109 are driven continuously so long as the main drive motor 107 is operated, and at constant properly related speeds and in opposite directions. The latter is important because it is desirable to have the print drum rotate in opposition to the direction of movement of the paper. On the other hand, the format and the paper drive group mechanisms are driven intermittently and for periods of time dependent upon the operation of the clutch 128 which, as stated in application Serial No. 138,157, is controlled by proper electronics signals gen erated between the electronics portion of the printer and the computer-buffer combination with which the printer is employed.

As stated above, the use of gears in this drive train has been kept to a minimum. Actually, the only gears employed are the meshing sets of gears 144-143 and 149- 150, which are necessarily employed merely to reverse the direction of rotation.

The timing wheel 265 (having magnetic slugs 268) is secured for rotation with the cam shaft 123. Magnetic pickup 26h is used with wheel 265 to signalthe position of the lobes of the earn 108. The timing wheel is rotationally adjustable on the cam shaft and this setting is intended to be made at the factory.

The code disk 310 is secured to rotate with the print drum 199, and it has associated with it photoelectric 4 means (not shown) for signaling which row of characters 161 is approaching the printing station along the row of print hammers (not shown) so as to be capable of being printed.

To obtain maximum printing speed from the printer, each cam lobe effects printing from a row of characters as it reaches the impacting position and as each row of characters on the print drum reaches the printing station;

in other words, a single print cycle with the use of the right lobe cam shown involves a 45 rotational angle of the cam, this 45 angle being the position of the next succeeding cam lobe with respect to the preceding cam lobe that is impacting the row of hammers. It is thus seen that the rotation of the cam and of the print drum must be so related that a cam lobe will be available to strike any addressed hammers every time a row of characters of the drum is presented at the printing station. For this reason, the pulley 153 is constructed so as to be angularly adjustable with respect to the print drum.

The 45 print cycle in terms of cam rotation is the equivalent of the angle between the center lines of adjacent rows of characters on the drum. Thus, if a different drum is employed having different spacing between rows of characters, then it will be necessary to change the timed relation between the cam and the drum. Accordingly, all of the pulleys and belts in the drive train are interchangeable so as to enable changing the speed ratios between the various parts of the printer.

It should be apparent that the number of lobes on the cam 108 and the spacing of the characters on the drum 1&9 could be changed, in which event the relative velocities of these elements and the printing speed would be different. This drive train design would readily permit such changes.

FIGURE 3 illustrates in greater detail the condition of the belt portion of the-drive train when the print drum and its shaft 361 are rotated to a vertical nonprint position on the pivot pin 274 shown in FIGURE 4, and it was stated above that this pivoting of the print drum can be accomplished without requiring subsequent readjustment of the drive mechanism. In order to prevent the belt 155 from changing its position on or slipping off the pulleys 152 and 153, a spring-loaded tensioning wheel 156 is provided, the wheel 156 being r-otatably mounted on a U-shaped retainer member 376 having a stern 377 slidable lengthwise in a guide passage 377a in the printer frame and biased toward the belt 155 by the compression spring 373 so as to at all times maintain tension in the belt 155. The retainer 376 has an additional pin 379 fixed thereto which is free of the belt 155 when the. drum 109 is in the print position, but which is engaged by the belt 155 when the drum arm is pivoted as shown in FIGURE 3. The longer leg 376a of the retainer prevents the upper portion of the belt 155 from being displaced laterally, and both legs of the retainer prevent the lower portion of the belt from being so displaced. It is apparent that the shorter leg 37612 of the retainer is free to move in the slot 377]) formed in the printer frame so as to prevent the retainer member 376 from rotating about the axis of the pin 377,thus insuring that the belt 155 cannot work its way free of the retainer.

The wheel 119a mounted for rotation on shaft 119is merely an idler to engage the belt 155 and assist in preventing its leaving the pulley 152..

It is apparent that the invention disclosed herein constitutes a relatively inexpensive, completely adjustable and quiet printer drive train by which the moving printer parts are driven at properly related speeds without slipping and with a substantially uniform velocity. Also, the drum arm may be pivoted between its print and non-print positions without changing the original relation of the drive between the cam and the print drum. The low inertia belt and pulley drive for the mechanism 11% enables a fast acting lower power'clutch mechanism 128.

While but one embodiment of the invention is shown and described, no limitations are intended except as recited in the appended claims.

We claim as our invention:

1. In a drum printer to print on paper, a frame, a rotary print drum on which characters to be printed are formed, means pivotably connecting said drum to said frame for movement from a first position in which said drum is operable for printing to a second position in which said drum is in a non-print location, an elongated cam for impacting print hammers against said print drum when in said first position, mechanism for driving the paper on which characters are to be printed, mechanism for controlling said paper drive mechanism, a clutch device, a drive train comprising a main drive motor, and a nonslipping belt and pulley means driven by said motor for driving said print drum and said cam and said paper drive mechanism and said control mechanism and said clutch device in a timed relationship, and mean for maintaining said relationship when said drum is pivoted to said second position at which the axis of said print drum is at approximately right angles with the axis of said elongated cam, said maintaining means including a retainer member for preventing lateral displacement of the belt associated with said print drum, a fixed member containing a hole therethrough, a stem fixed to said retainer member and slidably located in said hole, and resilient means compressed between said fixed member and said retainer member for maintaining tension in said belt when said belt is moved against said retainer member by the pivotal movement of said drum in moving between said first and said second positions.

2. In an on-the-fly printer to print on paper, a frame, a rotatable member on which characters to be printed are formed, an elongated cam in a parallel relationship with the axis of said rotatable member for impacting print hammers against said rotatable member, mechanism for driving the paper on which characters are to be printed, mechanism for controlling said paper drive mechanism, a clutch device, a drive train comprising a main drive mo tor, and a nonslipping belt and pulley means for driving said rotatable member and said cam and said paper drive mechanism and said control mechanism and said clutch device in a timed relationship, means pivotally connecting said rotatable member to said frame for movement between a first position and a non-operative position wherein the axis of said rotatable member is non-parallel to the axis of said elongated cam, and means for maintaining said belt means in an effective operative condition in either position of said rotatable member thereby maintaining the effective drive of said drive train to thereby maintain said timed relationship in moving said member 7 References Cited by the Examiner UNITED STATES PATENTS 1,393,693 10/21 Otti 74220 2,121,080 6/38 Galkin.

2,63 0,720 3 /5 3 Gambill 7 47 22 2,7 66,686 10/56 Fomenko et al.

2,796,830 6/57 Hilton.

2,884,852 5/59 Saltz.

2,915,966 12/59 Jacoby.

2,949,846 8/60 Hoffman et al.

2,990,767 7/ 61 Demer et al.

3,08 8,401 5/63 Shimabukuro.

WILLIAM B. PENN, Primary Examiner.

ROBERT A. LEIGHEY, Examiner. 

1. IN A DRUM PRINTER TO PRINT ON PAPER, A FRAME, A ROTARY PRINT DRUM ON WHICH CHARACTERS TO BE PRINTED ARE FORMED, MEANS PIVOTABLY CONNECTING SAID DRUM TO SAID FRAME FOR MOVEMENT FROM A FIRST POSITION IN WHICH SAID DRUM IS OPERABLE FOR PRINTING TO A SECOND POSITION IN WHICH SAID DRUM IS IN A NON-PRINT LOCATION, AN ELONGATED CAM FOR IMPACTING PRINT HAMMERS AGAINST SAID PRINT DRUM WHEN IN SAID FIRST POSITION, MECHANISM FOR DRIVING THE PAPER ON WHICH CHARACTERS ARE TO BE PRINTED, MECHANISM FOR CONTROLLING SAID PAPER DRIVE MECHANISM, A CLUTCH DEVIE, A DRIVE TRAIN COMPRISING A MAIN DRIVE MOTOR, AND A NONSLIPPING BELT AND PULLY MEANS DRIVEN BY SAID MOTOR FOR DRIVING SAID PRINT DRUM AND SAID CAM AND SAID PAPER DRIV MECHANISM AND SAID CONTROL MECHANISM AND SAID CLUTCH DEVICE IN A TIMED RELATIONSHIP, AND MEANS FOR MAINTAINING SAID RELATIONSHIP WHEN SAID DRUM IS PIVOTED TO SAID SECOND POSITION AT WHICH THE AXIS OF SAID PRINT DRUM IS AT APPROXIMATELY RIGHT ANGLES WITH THE AXIS OF SAID ELONGATED CAM, SAID MAINTAINING MEANS INCLUDING A RETAINER MEMBER FOR PREVENTING LATERAL DISPLACEMENT OF THE BELT ASSOCIATED WITH SAID PRINT DRUM, A FIXED MEMBER CONTAINING A HOLE THERETHROUGH, A STEM FIXED TO SAID RETAINER MEMBER AND SLIDABLY LOCATED IN SAID HOLE, AND RESILIENT MEANS COMPRESSED BETWEEN SAID FIXED MEMBER AND SAID RETAINER MEMBER FOR MAINTAINING TENSION IN SAID BELT WHEN SAID BELT IS MOVED AGAINST SAID RETAINER MEMBER BY THE PIVOTAL MOVEMENT OF SAID DRUM IN MOVING BETWEEN SAID FIRST AND SAID SECOND POSITIONS. 